From the flower seller a grim, crotchety, “Sold out!” (9)
I believe the answer is:
marigolds
'from the flower seller' is the definition.
I can't tell whether this defines the answer.
'a grim crotchety sold out' is the wordplay.
I cannot really understand how this works, but
'a' is present in the answer.
an anagram of 'grim' is 'mrig' which is within the remaining letters.
an anagram of 'sold' is 'olds' which is present in the answer.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for marigolds that I've seen before include "Yellow flowers" , "(flowery things)" .)